A method for limiting the amplitude of reciprocation of a piston reciprocating in a cylinder of a free-piston Stirling engine. The method is the combination of both at least partially covering the heat rejecter cylinder port by the piston sidewall during a peak part of the inward reciprocation of the piston and at least partially covering the heat rejecter cylinder port by the displacer sidewall during a peak part of the outward reciprocation of the displacer. The piston and the displacer, at times during their reciprocation, fully cover the effective heat rejecter cylinder port when the piston amplitude of reciprocation is large and approaches the physical limit of the amplitude of reciprocation in order to avoid internal collisions by a reciprocating component.

A heat engine includes two kinds of thermodynamic cycles, wherein a thermodynamic cycle 1 is composed of four processes: an isothermal exothermic compression process, an isochoric endothermic heating process, an isothermal endothermic expansion process and an isochoric exothermic cooling process, and the thermodynamic cycle 1 is composed of two loops, and the structure thereof includes a cylinder #1, a cylinder #2, a cylinder #3, a turbo expander or a double-shaft double-acting cylinder and an airproof container; and a thermodynamic cycle 2 is composed of three processes: an isothermal endothermic expansion and working process, an isobaric exothermic compression process and an isochoric endothermic heating process, and the thermodynamic cycle 2 is composed of two loops, and the structure thereof includes a heat insulating cylinder #1, a heat insulating cylinder #2, a condenser #1, a condenser #2, a cylinder #3, a turbo expander or a double-shaft double-acting cylinder and an airproof container.

A heat engine includes two kinds of thermodynamic cycles, wherein a thermodynamic cycle 1 is composed of four processes: an isothermal exothermic compression process, an isochoric endothermic heating process, an isothermal endothermic expansion process and an isochoric exothermic cooling process, and the thermodynamic cycle 1 is composed of two loops, and the structure thereof includes a cylinder #1, a cylinder #2, a cylinder #3, a turbo expander or a double-shaft double-acting cylinder and an airproof container; and a thermodynamic cycle 2 is composed of three processes: an isothermal endothermic expansion and working process, an isobaric exothermic compression process and an isochoric endothermic heating process, and the thermodynamic cycle 2 is composed of two loops, and the structure thereof includes a heat insulating cylinder #1, a heat insulating cylinder #2, a condenser #1, a condenser #2, a cylinder #3, a turbo expander or a double-shaft double-acting cylinder and an airproof container.

A monolithic heat exchanger body for inputting heat to a closed-cycle engine includes heating walls and heat sink, such as heat transfer regions. The heating walls are configured and arranged in an array of spirals or spiral arcs relative to a longitudinal axis of an inlet plenum. Adjacent portions of the heating walls respectively define corresponding heating fluid pathways fluidly communicating with the inlet plenum. At least a portion of the heat sink is disposed about at least a portion of the monolithic heat exchanger body. The heat sink includes working-fluid bodies including working-fluid pathways that have a heat transfer relationship with the heating fluid pathways. Respective ones of the heat transfer regions have a heat transfer relationship with a corresponding semiannular portion of the heating fluid pathways. Respective ones of the heat transfer regions include working-fluid pathways fluidly communicating between a heat input region and a heat extraction region.

A monolithic heat exchanger body for inputting heat to a closed-cycle engine includes heating walls and heat sink, such as heat transfer regions. The heating walls are configured and arranged in an array of spirals or spiral arcs relative to a longitudinal axis of an inlet plenum. Adjacent portions of the heating walls respectively define corresponding heating fluid pathways fluidly communicating with the inlet plenum. At least a portion of the heat sink is disposed about at least a portion of the monolithic heat exchanger body. The heat sink includes working-fluid bodies including working-fluid pathways that have a heat transfer relationship with the heating fluid pathways. Respective ones of the heat transfer regions have a heat transfer relationship with a corresponding semiannular portion of the heating fluid pathways. Respective ones of the heat transfer regions include working-fluid pathways fluidly communicating between a heat input region and a heat extraction region.

A near isothermal machine for compressing or expanding gas having a piston in a main cylinder with a heat absorbing and releasing structure attached thereto. The main cylinder contains a substantially constant volume of liquid maintained at a substantially constant temperature and a variable volume of gas, the gas temperature being controlled to substantially the same temperature as the liquid by the movement with the piston of the heat absorbing and releasing structure. A compensator is provided to compensate for variations in the level of liquid as the piston moves in the main cylinder.

A near isothermal machine for compressing or expanding gas having a piston in a main cylinder with a heat absorbing and releasing structure attached thereto. The main cylinder contains a substantially constant volume of liquid maintained at a substantially constant temperature and a variable volume of gas, the gas temperature being controlled to substantially the same temperature as the liquid by the movement with the piston of the heat absorbing and releasing structure. A compensator is provided to compensate for variations in the level of liquid as the piston moves in the main cylinder.

A monolithic heat exchanger body for inputting heat to a closed-cycle engine includes heating walls and heat sink, such as heat transfer regions. The heating walls are configured and arranged in an array of spirals or spiral arcs relative to a longitudinal axis of an inlet plenum. Adjacent portions of the heating walls respectively define corresponding heating fluid pathways fluidly communicating with the inlet plenum. At least a portion of the heat sink is disposed about at least a portion of the monolithic heat exchanger body. The heat sink includes working-fluid bodies including working-fluid pathways that have a heat transfer relationship with the heating fluid pathways. Respective ones of the heat transfer regions have a heat transfer relationship with a corresponding semiannular portion of the heating fluid pathways. Respective ones of the heat transfer regions include working-fluid pathways fluidly communicating between a heat input region and a heat extraction region.

A monolithic heat exchanger body for inputting heat to a closed-cycle engine includes heating walls and heat sink, such as heat transfer regions. The heating walls are configured and arranged in an array of spirals or spiral arcs relative to a longitudinal axis of an inlet plenum. Adjacent portions of the heating walls respectively define corresponding heating fluid pathways fluidly communicating with the inlet plenum. At least a portion of the heat sink is disposed about at least a portion of the monolithic heat exchanger body. The heat sink includes working-fluid bodies including working-fluid pathways that have a heat transfer relationship with the heating fluid pathways. Respective ones of the heat transfer regions have a heat transfer relationship with a corresponding semiannular portion of the heating fluid pathways. Respective ones of the heat transfer regions include working-fluid pathways fluidly communicating between a heat input region and a heat extraction region.

A constant density heat exchanger and method of operating are provided. The constant density heat exchanger includes a housing extending between a first end and a second end and defining a chamber having an inlet and an outlet. A first plate is positioned at the first end of the housing and rotatable about an axis of rotation such that the first plate selectively allows a working fluid to flow into the inlet of the chamber. A second plate is positioned at the second end of the housing and rotatable about the axis of rotation such that the second plate selectively allows the working fluid to flow out of the outlet of the chamber. The first plate and the second plate are rotatable about the axis of rotation so as to hold a volume of the working fluid at constant density as a heat source imparts thermal energy thereto.